Which substance has Hf defined as 0 kJ/mol? H2O (s) Ne (l) O2 (g) CO2 (g)

O₂ (g).

Explanation:

All elements that found in nature has heat of formation (Hf) equal 0 J/mol. So, the substance that has heat of formation (Hf) equal 0 J/mol is O₂ (g). H₂O is formed from the reaction of hydrogen and oxygen and has Hf, Also, the solidification of H₂O (s) from H₂O (l) has (Hf). Although, Ne (g) is found in nature and has no Hf, the liquification to form Ne (l) has heat of formation (Hf). CO₂ (g) is formed from the reaction between carbon and oxygen and so has heat of formation (Hf).

O2 (g)

Explanation:

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